During operation of a piston-cylinder type internal combustion engine, reciprocal movement of the pistons in the cylinders creates pressure pulses within the various chambers of the engine. For example, during an intake or expansion stroke of the piston, pressure within the crankcase of the engine generally increases, whereas during a compression or exhaust stroke of the piston, pressure within the crankcase of the engine generally decreases. The pressure pulses in the crankcase are communicated to other chambers within the engine, such as the rockerbox area, via breather passages, oil flow passageways, and the like. To reduce internal engine losses, often referred to as “pumping losses,” many internal combustion engines utilize a breather system that operates to dissipate the pressure pulses within the crankcase, the rockerbox, and other chambers of the engine.
Movement of various internal engine components also creates an oil mist that is carried throughout the engine by the pressure pulses. Environmental concerns are such that it is preferred to separate as much of the oil mist as possible from the gasses that may be expelled from the engine through the breather system. Many breather systems remove the oil mist from the air by routing the internal engine gasses through screens, meshes, and various serpentine paths before discharging the gasses to the atmosphere. To further reduce emissions to the atmosphere, some breather systems route some or all of the gasses expelled from the breather system to the engine's air/fuel intake stream (e.g. to the airbox or to the intake manifold).